"You need a bullpen to do what ours did tonight from the sixth on - put up zeros," Rockies manager Bud Black said. "That's the expectation, and that's their expectation."

Colorado trailed 8-6 when McMahon pinch-hit with two on and two outs in the fifth. He sent a 1-0 changeup from reliever Robert Gsellman into the Rockies' bullpen to give Colorado the lead.

It was McMahon's second homer of the season and it came just hours after he worked with hitting coach Duane Espy in the batting cage.

"I made a small adjustment today with my hands, just put them in a better position to get that shorter swing off, that flatter swing off," McMahon said. "Stood the bat up a little more and got instant results.

"It's been a long time coming and it felt really good to come through for the guys."

Gsellman (5-2) had given up just one home run in 16 road games prior to Wednesday.

"A changeup right down the middle and the hitter just did his job and hit it out of the ballpark," he said. "Got to execute the pitch."

Bryan Shaw (3-5) got one out to earn the win. Wade Davis pitched the ninth for his 21st save this season - and the 100th of his career.

New York took an 8-6 lead with a four-run fifth. The Mets batted around for the second time in the game and benefited from three walks in the inning, including one to Brandon Nimmo with the bases loaded.

Dominic Smith, who tripled in the fifth, had a career-high three hits for New York and was a home run short of the cycle.

The Mets loaded the bases in the sixth against lefty Harrison Musgrave but pinch-hitter Kevin Plawecki grounded into an inning-ending double play to Arenado at third.

"The sixth got a little dicey, but zeros nevertheless," Black said. "That's how you win games."

Neither starter lasted long in another high-scoring game at Coors Field. The Mets scored three in the first and another in the second to take a 4-1 lead, but Colorado tied it with three unearned runs in the second.

Mets: RHP A.J. Ramos had arthroscopic surgery on his right shoulder. ... Mets manager Mickey Callaway said the results of OF Jay Bruce's MRI revealed a right hip strain and the team will decide on a plan soon. ... RHP Noah Syndergaard (strained ligament in right index finger) threw before batting practice.

Rockies: LHP Mike Dunn (rhomboid strain) threw live batting practice and said he had no ill effects. Dunn said he threw about 20 pitches. If he feels good Thursday, Black said Dunn could go on a rehab assignment this weekend. ... RHP Scott Oberg (back strain) could also go on a rehab assignment, Black said.

INJURY SCARE

New York second baseman Asdrubal Cabrera was holding his left arm after tagging out Murphy on a steal attempt in the seventh inning. The trainer checked him over but Cabrera was able to stay in the game.

"He just landed hard on his left elbow," Callaway said.

HOME INVASION

The Rockies have allowed eight or more runs in their last nine home games, which ties for the longest streak in big league history, according to the Elias Sports Bureau. The 1894 St. Louis Browns were the last team to do it.

ROSTER MOVE

Before the game, the Mets recalled RHP Chris Flexen from Triple-A Las Vegas and optioned RHP Hansel Robles to their top farm team.

UP NEXT

In a matchup of left-handers, the Mets will send Steven Matz (3-4, 3.31 ERA) to the mound against Colorado hometown favorite Kyle Freeland (6-6, 3.59) in the finale of the four-game series Thursday afternoon.